Aqueous dispersion of flame retardant for textiles and process for producing same

ABSTRACT

Flame retardant aqueous dispersions or suspensions comprising tris(tribromophenoxy)-s-triazine (TTBT) or tetrabromobisphenol A bis(2,3-dibromopropyl ether) (TBBPE) or a mixture thereof and one or more nonionic or anionic surface active agent(s) and/or wetting agent(s) used in textile are described. The flame retardants exhibit high compatibility with textile materials and are stable in aqueous solutions.

FIELD OF THE INVENTION

The present invention relates to flame retardant aqueous dispersions that are used in textile. More particularly, the invention relates to the use of flame retardants which exhibit a high compatibility with textile materials and which are stable in aqueous solution.

BACKGROUND OF THE INVENTION

Flame retardation of textiles using aromatic bromine-containing formulations adhered to the substrates by means of binders, has been long established (for instance, U.S. Pat. No. 3,955,032 and U.S. Pat. No. 4,600,606). The main drawbacks of existing formulations include high bromine content demand, high dry add-on demand, streak marks on dark fabrics, excessive dripping during combustion of thermoplastic fibers and dispersion instability. Most of these drawbacks are inherent to the aromatic bromine compounds used.

Using existing aromatic bromine containing formulations, the percentage resin component may be as high as 60-70 wt % of the total add-on in order to obtain satisfactory flame retardation (see Toxicological Risks of Selected Flame-Retardant Chemicals (2000), by Donald E. Gardner (Chair) Subcommittee on Flame-Retardant Chemicals, Committee on Toxicology, Board on Environmental Studies and Toxicology, National Research Council page 507). This high add-on is due in part to the large amount of binder needed to fix the flame retardant (FR) agents to the textile. The binder may be as high as 50 wt % of the total FR formulation (see Toxicological Risks of Selected Flame-Retardant Chemicals (2000) page 507). Due to its substantial presence, the binder contributes to flammability and dripping, which requires more bromine content, thus creating an inefficient cycle. In order to obtain flame retarded textiles with better performance and less detriment to textile properties, an efficient FR agent conducive to incorporation in low binder content formulations with good dispersion properties is required.

Tris(tribromophenoxy)-s-triazine (FR-245) is a flame retardant with a combination of aromatic bromine and cyanurate that provides high FR efficiency and good thermal stability. In its non-micronized form it is useful in many applications, especially but not exclusively, in the field of fire retardants for plastic compositions. FR-245 is insoluble in water but has a specific gravity of about 2.4, significantly lower than bromine rich FR agents commonly used in such applications such as Decabromodiphenyl Oxide (Deca), which has a specific gravity of 3. FR-245 is also easily micronized. Therefore, FR-245 lends itself to the preparation and use of more stable aqueous dispersions. FR-245 also has a higher initial decomposition temperature than Decabromodiphenyl oxide.

Tetrabromobisphenol A bis(2,3-dibromopropyl ether) (FR-720) is a flame retardant with a combination of aromatic and aliphatic bromine that provides high FR efficiency and good thermal stability. FR-720 is useful in many applications, especially but not exclusively, in the field of fire retardants for plastic compositions. FR-720 is insoluble in water but has a specific gravity of about 2.3, significantly lower than bromine rich FR agents commonly used in such applications such as Decabromodiphenyl Oxide (Deca). FR-720 has an advantage in that a homogenous film can be achieved during the application due to its low melting range (113-117° C.) which enables melt penetration of the material being processed.

It has now been surprisingly found, and this is an object of the present invention, that two specific aromatic flame-retardants, never tested before in textile, possess unexpected stability and compatibility properties, which render them highly efficient for the purpose of flame-retarding textile materials.

It is thus a purpose of this invention to provide stable dispersions or suspensions of A) tris(tribromophenoxy)-s-triazine or B) tetrabromobisphenol A bis(2,3-dibromopropyl ether), or of mixtures thereof, which alleviate the drawbacks of existing formulations for treating textile materials.

It is another purpose of this invention to provide such dispersions or suspensions that are aqueous dispersions or suspensions and which do not require non-aqueous solvents.

It is a further purpose of this invention to provide a process for preparing such aqueous dispersions or suspensions.

It is yet another purpose of the invention to provide dispersions of tris(tribromophenoxy)-s-triazine or tetrabromobisphenol A bis(2,3-dibromopropyl ether) or of a blend of tris(tribromophenoxy)-s-triazine and tetrabromobisphenol A bis(2,3-dibromopropyl ether) for particular uses in the textile industry by coating and/or padding and/or foaming and/or spraying application.

It is still a further purpose of the invention to provide dispersions of tris(tribromophenoxy)-s-triazine or tetrabromobisphenol A bis(2,3-dibromopropyl ether) or a blend of tris(tribromophenoxy)-s-triazine and tetrabromobisphenol A bis(2,3-dibromopropyl ether) together with additional compounds, such as synergists for increasing the fire-retarding efficiency of compositions obtained from these flame retardants.

It is still another purpose of the invention to provide dispersions of tris(tribromophenoxy)-s-triazine or tetrabromobisphenol A bis(2,3-dibromopropyl ether) or a blend of tris(tribromophenoxy)-s-triazine and tetrabromobisphenol A bis(2,3-dibromopropyl ether) with significantly reduced amounts of binder content.

It is also a purpose of the invention to produce a smooth, translucent coating of tris(tribromophenoxy)-s-triazine or tetrabromobisphenol A bis(2,3-dibromopropyl ether) or a blend of tris(tribromophenoxy)-s-triazine and tetrabromobisphenol A bis(2,3-dibromopropyl ether) on textile materials, when applied in aqueous solution.

Other purposes and advantages of the invention will become apparent as the description proceeds.

SUMMARY OF THE INVENTION

The dispersion of tris(tribromophenoxy)-s-triazine or tetrabromobisphenol A bis(2,3-dibromopropyl ether) or a blend of tris(tribromophenoxy)-s-triazine and tetrabromobisphenol A bis(2,3-dibromopropyl ether), according to the invention, is characterized in that it comprises one or both of the above flame retardants, or mixtures thereof, and contains nonionic or anionic surface-active agents or wetting agents.

The nonionic or anionic surface-active agents or wetting agents useful in the invention are well known in the art and can be chosen by the skilled person without the need for experimentation. Illustrative and non-limitative examples of nonionic agents include, for instance, polyoxyethylene (POE) alkyl ether type, preferably NP-6 (Nonylphenol ethoxylate, 6 ethyleneoxide units).

Illustrative and non-limitative examples of anionic agents include, for instance, free acids or organic phosphate esters or the dioctyl ester of sodium sulfosuccinic acid.

The dispersion of the invention may also include other additives which function both as dispersing agents and suspending agents and which are commonly used by persons skilled in the art, such as acrylic acids/acrylic acids ester copolymer neutralized—sodium polycarboxyl, preferably naphthalene sulfonic acid—formaldehyde condensate sodium salt.

The suspension according to the invention may also include defoaming or antifoaming agents, which are well known to persons skilled in the art. These may include, for example, emulsion of mineral oils or emulsion of natural oils or preferably emulsion of silicon oils like AF-52™.

The suspension according to the invention may also include binder agents, which are well known to persons skilled in the art. These may include, a polymer latex emulsion comprising of any acrylic co-monomers. For example, acrylic acid and methacrylic acid or their derivatives such as esters, nitrites and amides can be employed. The esters are preferred compounds. Specific examples of the acrylates that can be utilized are methyl acrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, isobutyl acrylate, isobutyl methacrylate, amyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, vinyl acrylate, allyl acrylate, hydroxyethyl acrylate, perfluoroethyl acrylate, isobornyl acrylate, phenoxyethyl acrylate, tetraethylene glycol diacrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, stearyl acrylate or stearyl methacrylate, acrylamide, methacrylamide, N—(C₁-C₈-alkyl acrylamides or—methacrylamides. A single acrylate or various combinations of acrylates can be employed in making the copolymers. In addition, other co-monomers may be employed in the copolymer latex including vinyl esters of saturated C₁-C₈-carboxylic acids, such as vinyl acetate, vinyl propionate, vinyl butyrate or vinyl stearate, styrene, phenoxyethyl acrylate, hydroxyalkylene monoacrylic esters and hydroxyalkylene monomethacrylic esters or acrylic esters and methacrylic esters of ethoxylated C₁-C₁₈-alcohols.

Other suitable illustrative textile binders are Acrylonitile-Butadiene-Styrene Copolymer, Polychloroprene Rubber and Carboxylated styrene butadiene rubber Polyurethane

Preserving or stabilizing agents such as formaldehyde, and preferably a mixture of methyl and propyl hydroxy benzoates, can also be added to the dispersion.

According to a preferred embodiment of the invention, dispersions of tris(tribromophenoxy)-s-triazine or tetrabromobisphenol A bis(2,3-dibromopropyl ether) or a blend of tris(tribromophenoxy)-s-triazine and tetrabromobisphenol A bis(2,3-dibromopropyl ether) are mixed together with additional compounds—such as fire-retardant synergists, e.g. fire-retardant antimony oxide (AO).

According to another preferred embodiment of the invention dispersions of tris(tribromophenoxy)-s-triazine or tetrabromobisphenol A bis(2,3-dibromopropyl ether) or a blend of tris(tribromophenoxy)-s-triazine and tetrabromobisphenol A bis(2,3-dibromopropyl ether) are incorporated in formulations with typically 30% or less, preferably 27% or less binder by weight.

According to still another preferred embodiment of the invention, formulations of tris(tribromophenoxy)-s-triazine or tetrabromobisphenol A bis(2,3-dibromopropyl ether) or a blend of tris(tribromophenoxy)-s-triazine and tetrabromobisphenol A bis(2,3-dibromopropyl ether) are used to impart satisfactory flame retardancy to textiles with less than 60% dry add-on, preferably 50% dry add-on, most preferably with 40% dry add-on by weight.

According to yet another preferred embodiment of the invention formulations of tris(tribromophenoxy)-s-triazine or tetrabromobisphenol A bis(2,3-dibromopropyl ether) or a blend of tris(tribromophenoxy)-s-triazine and tetrabromobisphenol A bis(2,3-dibromopropyl ether) are used to impart satisfactory flame retardancy to textiles after washing with detergent.

According to a preferred embodiment of the invention formulations of tris(tribromophenoxy)-s-triazine or tetrabromobisphenol A bis(2,3-dibromopropyl ether) or a blend of tris(tribromophenoxy)-s-triazine and tetrabromobisphenol A bis(2,3-dibromopropyl ether) are used to impart a smooth, translucent, non streaky coating on the textile substrates.

The dispersions, in particular the aqueous dispersions, of the invention are stable. When stored at room temperature, they are stable for at least two weeks and preferably at least one month. Their stability may be higher, e.g. three months or more.

The above and other characteristics and advantages of the invention will be better understood through the following illustrative and non-limitative detailed description of preferred embodiments thereof, with reference to the following examples.

EXAMPLE 1 Preparation of a Dispersion of Tris(Tribromophenoxy)-s-triazine (FR-245)

248 gr. of FR-245 with a size distribution ranging from 0.1 micron to 20 microns was added drop-wise to a mixed solution of 164 gr. of deionized water and 25 gr. of dispersing agent. 100 gr. Sb₂O₃ was added to the mixed dispersion. The dispersion was allowed to mix for fifteen minutes. About 5 gr. of acrylic thickener was added during mixing and the dispersion was neutralized to pH=7 using ammonium hydroxide. The composition of the dispersion is detailed in Table I below.

TABLE I Dispersion Viscosity (cP) 40 000    PH 7  FR in dispersion (wt %) 45.8 Br in dispersion (wt %) 30.7 Sb₂O₃ in dispersion (wt %) 18.5

The FR-245 dispersion was smooth, white and had good fluidity. The dispersion was left on a shelf for 6 months and remained stable (no settling was observed) during this period.

EXAMPLE 2 Preparation of a Formulation of FR-245

58 gr. of deionized water and 58 gr. of acrylic binder were added to 79 gr. of dispersion from Example 1. 19 gr. of acrylic thickener was added while mixing and the dispersion was neutralized to pH=7-8 using ammonium hydroxide. Details of the dispersion are given in Table II below.

TABLE II Dispersion Viscosity (cP) 28000 PH 7-8 FR in dispersion (wt %) 16.8 Br in dispersion (wt %) 11.3 Sb₂O₃ in dispersion (wt %) 6.8

This formulation contained 27% by weight of binder, 16.8 wt % FR agent and 11.3 wt % bromine content. The FR-245 formulation was smooth, white and had good fluidity. The dispersion was left on a shelf for 6 months and remained stable (no settling was observed) during this period.

EXAMPLE 3 Application of FR-245 Formulation to Polyester Fabric

Polyester fabric weighing 164 grams per square meter was coated using a knife coater with the formulation from Example 2 to 57.7% dry add-on and cured. The fabric passed ASTM D 6413-99 with negligible dripping. The fabric was translucent with no visible streak marks.

EXAMPLE 4 Application of FR-245 Formulation to Polyester Fabric

Polyester fabric weighing 164 grams per square meter was coated using a knife coater with the formulation from Example 2 to 40% dry add-on and cured. The fabric passed ASTM D 6413-99 with negligible dripping. The fabric was translucent with no visible streak marks.

EXAMPLE 5 Application of FR-245 Formulation to Polyester Fabric

Polyester fabric weighing 164 grams per square meter was coated using a knife coater with the formulation from Example 2 to 40% dry add-on and cured. The fabric was washed with 1 gram per liter standard detergent at 80° C. for 30 minutes and dried. The fabric passed ASTM D 6413-99 with negligible dripping. The fabric was translucent with no visible streak marks.

EXAMPLE 6 Preparation of a Dispersion of Tetrabromobisphenol A bis(2,3-dibromopropyl Ether) (FR-720)

248 gr. of FR-720 was added drop-wise to a mixed solution of 241 gr. of deionized water and 36 gr. of dispersing agents. 100 gr. Sb₂O₃ was added to the mixed dispersion. The dispersion was allowed to mix for fifteen minutes. About 7.3 gr. of acrylic thickener was added during mixing and the dispersion is neutralized to pH=7 using ammonium hydroxide. Details of the dispersion are given in Table III below.

TABLE III Dispersion Viscosity (cP) 40 000    PH 7  FR in dispersion (wt %) 39.2 Br in dispersion (wt %) 26.5 Sb₂O₃ in dispersion (wt %) 15.8

The FR-720 dispersion was smooth, white and had good fluidity. The dispersion was left on a shelf for 6 months and remained stable (no settling was observed) during this period.

EXAMPLE 7 Preparation of a Formulation of FR-720

140 gr. of deionized water and 145 gr. of acrylic binder were added to 198 gr. of dispersion from Example 6. 18.4 gr. of acrylic thickener was added during mixing and the dispersion was neutralized to pH=7-8 using ammonium hydroxide. Details of the dispersion are given in Table IV below.

TABLE IV Dispersion Viscosity (cP) 16400 PH 7-8 FR in dispersion (wt %) 15.9 Br in dispersion (wt %) 10.7 Sb₂O₃ in dispersion (wt %) 6.4

This formulation contained 34.2% by weight of binder, 15.9% FR agent and 10.7% bromine content. The formulation was smooth, white and had good fluidity. The dispersion was left on a shelf for 6 months and remained stable (no settling was observed) during this period.

EXAMPLE 8 Application of FR-720 Formulation to Polyester Fabric

Polyester fabric weighing 164 grams per square meter was coated using a knife coater with the formulation from Example 7 to 35% dry add-on and cured. The fabric passed ASTM D 6413-99 with negligible dripping. The fabric was translucent with no visible streak marks.

EXAMPLE 9 Preparation of a Dispersion of FR-245/FR-720 Blend

248 gr. of FR-245/FR-720 1:1 blend was added drop-wise to a mixed solution of 315 gr. of deionized water and 25 gr. of dispersing agent. 100 gr. Sb₂O₃ was added to the mixed dispersion. The dispersion was allowed to mix for fifteen minutes. About 6.6 gr. of acrylic thickener was added during mixing and the dispersion was neutralized to pH=7 using ammonium hydroxide. Details of the dispersion are given in Table V below.

TABLE V Dispersion Viscosity (cP) 40 000    PH 7  FR in dispersion (wt %) 35.7 Br in dispersion (wt %) 23.9 Sb₂O₃ in dispersion (wt %) 14.4

The FR-245/FR-720 1:1 blend dispersion was smooth, white and had good fluidity. The dispersion was left on a shelf for 6 months and remained stable (no settling was observed) during this period.

EXAMPLE 10 Preparation of a Formulation of FR-245/FR-720 Blend

145 gr. of deionized water and 145 gr. of acrylic binder were added to 198 gr. of dispersion from Example 9. 17 gr. of acrylic thickener was added during mixing and the dispersion was neutralized to pH=7-8 using ammonium hydroxide. Details of the dispersion are given in Table VI below.

TABLE VI Dispersion Viscosity (cP) 9600 PH 7-8 FR in dispersion (wt %) 13.7 Br in dispersion (wt %) 9.2 Sb₂O₃ in dispersion (wt %) 5.5

This formulation contained 38% by weight of binder, 13.7% FR agent and 9.2% bromine content. The FR-245/FR-720 1:1 blend formulation was smooth, white and had good fluidity. The dispersion was left on a shelf for 6 months and remained stable (no settling was observed) during this period.

EXAMPLE 11 Application of FR-245/FR-720 Blend Formulation to Polyester Fabric

Polyester fabric weighing 164 grams per square meter was coated using a knife coater with the formulation from Example 10 to 44% dry add-on and cured. The blend film was transparent and soft. The fabric passed ASTM D 6413-99 with negligible dripping. The fabric was translucent with no visible streak marks.

While examples of the invention have been described for purposes of illustration, it will be apparent that many modifications, variations and adaptations can be carried out by persons skilled in the art, without exceeding the scope of the claims. 

1. A dispersion comprising tris(tribromophenoxy)-s-triazine or tetrabromobisphenol A bis(2,3-dibromopropyl ether) or a mixture thereof and one or more nonionic or anionic surface-active agent(s) and/or wetting agent(s).
 2. A dispersion according to claim 1, wherein the nonionic agent is selected from among polyoxyethylene (POE) alkyl ether type, preferably NP-6 (Nonylphenol ethoxylate, 6 ethyleneoxide units).
 3. A dispersion according to claim 1, wherein the anionic agent is selected from free acids or organic phosphate esters or the dioctyl ester of sodium sulfosuccinic acid.
 4. A dispersion according to claim 1, wherein the comprising one or more additive(s) which function both as dispersing agents and suspending agents.
 5. A dispersion according to claim 4, wherein the one or more additive(s) are selected from among acrylic acids/acrylic acids ester copolymer neutralized—sodium polycarboxyl, preferably naphthalene sulfonic acid—formaldehyde condensate sodium salt.
 6. A dispersion according to claim 1, further comprising one or more defoaming or antifoaming agent(s).
 7. A dispersion according to claim 6, wherein the defoaming or antifoaming agents are selected from among emulsion of mineral oils or emulsion of natural oils or, preferably, emulsion of silicon oils such as AF-52™.
 8. A dispersion according to claim 1, further comprising one or more preserving or stabilizing agent(s).
 9. A dispersion according to claim 8, wherein the one or more preserving or stabilizing agent(s) are selected from among formaldehyde and a mixture of methyl and propyl hydroxy benzoates.
 10. A dispersion according to claim 1, further comprising fire-retardant synergists.
 11. A dispersion according to claim 10, wherein the fire-retardant synergist is antimony oxide (AO).
 12. A dispersion according to claim 1, which is are stable for at least two weeks when stored at room temperature.
 13. A dispersion according to claim 12, which is are stable for at least one month when stored at room temperature.
 14. A dispersion according to claim 1, further comprising binder agents.
 15. The dispersion of claim 14, wherein the binder agents are selected from among a polymer latex emulsion comprising of an acrylic co-monomer.
 16. The dispersion of claim 15, wherein the acrylic co-monomer comprises acrylic acid or methacrylic acid or their derivatives such as esters, nitrites and amides.
 17. The dispersion of claim 16, wherein the acrylate is selected from among methyl acrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, isobutyl acrylate, isobutyl methacrylate, amyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, vinyl acrylate, allyl acrylate, hydroxyethyl acrylate, perfluoroethyl acrylate, isobornyl acrylate, phenoxyethyl acrylate, tetraethylene glycol diacrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, stearyl acrylate or stearyl methacrylate, acrylamide, methacrylamide, N—(C₁-C₈-alkyl acrylamides or—methacrylamides, and co-monomers of two or more of said acrylates.
 18. The dispersion of claim 14, wherein the binder agents are selected from among copolymers made from co-monomers including vinyl esters of saturated C₁-C₈-carboxylic acids, such as vinyl acetate, vinyl propionate, vinyl butyrate or vinyl stearate, styrene, phenoxyethyl acrylate, hydroxyalkylene monoacrylic esters and hydroxyalkylene monomethacrylic esters or acrylic esters and methacrylic esters of ethoxylated C₁-C₁₈-alcohols.
 19. The dispersion of claim 14 wherein the binder is selected from among Acrylonitile-Butadiene-Syrene Copolymer, Polychloroprene Rubber and Carboxylated styrene butadiene rubber Polyurethane.
 20. A flame-retardant composition for use in textile, comprising a dispersion of tris(tribromophenoxy)-s-triazine or of tetrabromobisphenol A bis(2,3-dibromopropyl ether), or a mixture thereof, and one or more nonionic or anionic surface-active agent(s) and/or wetting agent(s).
 21. A composition according to claim 20, wherein the dispersion is incorporated in formulations with 30% or less, preferably 27% or less, binder by weight.
 22. A composition according to claim 20, wherein the dispersion is used to impart satisfactory flame retardancy to textiles with less than 60% dry add-on, preferably less 50% dry add-on, most preferably about 40% dry add-on by weight.
 23. A composition according to claim 20, which maintains satisfactory flame retardancy (according to ASTM D 6413-99 or other applicable standards) in textiles after washing with detergents.
 24. A composition according to claim 20, which imparts a smooth, translucent, non streaky coating on the textile substrates.
 25. Use of a dispersion comprising tris(tribromophenoxy)-s-triazine or tetrabromobisphenol A bis(2,3-dibromopropyl ether), or a mixture thereof, as a flame-retardant in textile materials. 